1. Field of the Invention
The present invention relates to a three terminal magnetic head using a three terminal magnetoresistance device in a head for magnetically reproducing information recorded magnetically and to an ultrahigh-density magnetic recording/reproducing apparatus comprising the three terminal magnetic head.
2. Description of the Related Art
For use in a reproducing portion of a magnetic head used in a high-density magnetic recording apparatus, a CIP-GMR (Current-In-Plane Giant Magnetoresistance) device which allows a current to flow in the in-plane direction of a film and a tunnel magnetoresistance device have been proposed, which are disclosed in Japanese Unexamined Patent Publication No. HEI 4-358310 (Patent Document 1) and Japanese Unexamined Patent Publication No. HEI 10-4227 (Patent Document 2), respectively. On the other hand, “Physical Review Letters. Vol. 85, 3277 (2000) (Non-Patent Document 1) has recently reported the room-temperature operation of a three terminal spin transistor capable of producing an output several tens of times as large as outputs produced by these magnetoresistance devices, the application of which to a magnetic head has been expected. The higher output of the three terminal spin transistor has been achieved by using a Co/Cu/Co giant magnetoresistance device for the base of a transistor structure and injecting hot electrons into the GMR device by using a Schottky barrier formed at the semiconductor (emitter)/metal (base) interface. Although the injection of hot electrons is effective in increasing the output of the MR device, a problem is encountered that a collector current outputted with a metal/semiconductor Schottky barrier thus far reported is on the order of 1 nA, which is extremely small.